Brahms and Liszt with real fan, as Liszt was of Wagner (6-2-3)

I believe the answer is:
father-in-law
'liszt was of wagner' is the definition.
I can't tell whether this defines the answer.
'brahms and liszt with real fan' is the wordplay.
'brahms and liszt' indicates an anagram (Cockney rhyming slang for 'pissed', i.e. drunk).
'with'+'real'+'fan'='withrealfan'
'withrealfan' with letters rearranged gives 'FATHER-IN-LAW'.
'as' is the link.
Can you help me to learn more?
I've seen this clue in The Independent.
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